Closest gameobject in Line of Sight?

Hello

I'm attempting to create some AI for my game. I have them using a closest target function. I'm using unity reference code to find the closest targets.

Code (CSharp):

1. GameObject FindClosestEnemy()
2.     {
3.         GameObject[] gos;
4.         gos = GameObject.FindGameObjectsWithTag(EnemyFaction);
5.         GameObject closest = null;
6.         float distance = Mathf.Infinity;
7.         Vector3 position = transform.position;
8.         foreach (GameObject go in gos)
9.         {
10.             Vector3 diff = go.transform.position - position;
11.             float curDistance = diff.sqrMagnitude;
12.             if (curDistance < distance)
13.             {
14.                 closest = go;
15.                 distance = curDistance;
16.             }
17.         }
18.         return closest;
19.     }

However my AI sometimes finds the closest target which is on the other side of a wall. I know I have to use raycasts to find the line of sight of the target. However I was wondering if anyone knows away how this FindClosestEnemy function can check to see if the target is in a line of sight?

Because I have it so the AI won't attack enemies it can't see, however if an enemy is standing beside it in another room it'll attempt to target it instead of an enemy in front of it just slightly further away.

Thank you for you time.

 

can check with vector3.dot,
https://docs.unity3d.com/ScriptReference/Vector3.Dot.html

made one similar test here while ago,
http://unitycoder.com/blog/2012/12/09/enemy-visibility-cone/

 

Okay thanks, I never knew about that command. Would you say it's possible to put the vector3.dot into the closest gameobject function? Sorry for the follow up question.

 

yes, can put it there, maybe could check Dot first (to see if the target is in view at all),
only then check for distances to get closest within view.

 

Thank you for the help. I got it running. You are beyond amazing!

 

Hi,

Please, check this code. I wrote it to find the nearest exit. Then, at the movement phase I checked the distance to the nearest exit until the agent reached it.

I hope it can be helpful for you and others.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine.AI;
5.  
6. public class AgentController : MonoBehaviour {
7.     public float preMouvementTime = 0f ;
8.     private bool preMovementPhaseFinished = false;
9.     public GameObject[] knownExits;
10.     private GameObject target;
11.     NavMeshAgent navMeshAgent;
12.     //Animator animator;
13.  
14.     // Use this for initialization
15.     void Awake ()
16.     {
17.         navMeshAgent = GetComponent<NavMeshAgent>();
18.         target = new GameObject();
19.     }
20.  
21.     void Start()
22.     {
23.         target = nearestExit();
24.  
25.        
26.         //Debug.Log(target);
27.     }
28.    
29.     // Update is called once per frame
30.     void Update ()
31.     {
32.         float dist = Mathf.Infinity;
33.  
34.         if (!preMovementPhaseFinished)
35.             StartCoroutine(preMouvementPhase());
36.         else
37.         {
38.             //Mouvement Phase
39.             navMeshAgent.destination = target.transform.position;
40.            
41.  
42.             //calculate remaining distance to reach the target
43.             dist = calculatePathLength(target.transform.position);
44.            
45.             if (dist <= navMeshAgent.stoppingDistance + 0.1f)
46.             {
47.                 navMeshAgent.gameObject.SetActive(false);
48.                 Debug.Log(navMeshAgent.gameObject.name + " Exit time = " + Time.realtimeSinceStartup + "s");
49.  
50.             }
51.         }
52.  
53.         //Debug.Log(dist);
54.  
55.  
56.     }
57.  
58.     GameObject nearestExit()
59.     {
60.         GameObject nearestTarget = null;
61.  
62.         float[] distancesToKnownExits = new float[knownExits.Length];
63.  
64.         float minDistance = 9999f;
65.  
66.         for (int i = 0; i < knownExits.Length; i++)
67.         {
68.             distancesToKnownExits[i] = calculatePathLength(knownExits[i].transform.position);
69.  
70.             //Debug.Log(knownExits[i] + " " +  distancesToKnownExits[i]);
71.         }
72.  
73.         for (int i = 0; i < distancesToKnownExits.Length; i++)
74.         {
75.             if (distancesToKnownExits[i] <= minDistance)
76.             {
77.                 minDistance = distancesToKnownExits[i];
78.                 nearestTarget = knownExits[i];
79.             }
80.         }
81.  
82.         return nearestTarget;
83.     }
84.  
85.     float calculatePathLength(Vector3 targetPosition)
86.     {
87.         NavMeshPath path = new NavMeshPath();
88.        
89.         float pathLength = 0f;
90.  
91.         if (navMeshAgent.enabled)
92.         {
93.             NavMesh.CalculatePath(transform.position,targetPosition,NavMesh.AllAreas, path);
94.         }
95.  
96.         for (int i = 0; i < path.corners.Length - 1; i++)
97.             Debug.DrawLine(path.corners[i], path.corners[i + 1], Color.red);
98.  
99.         Vector3[] allWayPoints = new Vector3[path.corners.Length + 2];
100.  
101.         allWayPoints[0] = this.gameObject.transform.position - this.gameObject.transform.up;
102.         allWayPoints[allWayPoints.Length-1] = targetPosition;
103.  
104.         //Debug.Log(path.corners.Length);
105.         //Debug.Log(allWayPoints.Length);
106.  
107.         for (int i = 0; i < path.corners.Length; i++)
108.         {
109.             allWayPoints[i + 1] = path.corners[i];
110.         }
111.  
112.         for (int i = 0; i < allWayPoints.Length-1; i++)
113.         {
114.             pathLength += Vector3.Distance(allWayPoints[i], allWayPoints[i+1]);
115.         }
116.  
117.  
118.        
119.         return pathLength;
120.     }
121.  
122.     private IEnumerator preMouvementPhase()
123.     {
124.         //Debug.Log("Pre Movement Phase Started");
125.         yield return new WaitForSeconds(preMouvementTime);
126.         preMovementPhaseFinished = true;
127.  
128.     }
129. }
130.  

 

Hey thanks for the extra information! I'm very grateful!

 

Here's what I do. I create sensors that can be attached as components to a GameObject. Which are then referenced in my AI scripts as possible eyes.
https://github.com/lordofduct/spacepuppy-unity-framework/tree/master/SpacepuppyAI/AI/Sensors/Visual

They get to see 'VisualAspects' that are attached to the entities that are visible.

These sensors will return true if an entity is inside the confines of said sensor. Here you can see the outline of the sensor on our zombies in our current game:


Now how it might be used is like here in my AI script:

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections.Generic;
4. using System.Linq;
5.  
6. using com.spacepuppy;
7. using com.spacepuppy.AI;
8. using com.spacepuppy.AI.Sensors;
9. using com.spacepuppy.AI.Sensors.Visual;
10. using com.spacepuppy.Pathfinding;
11. using com.spacepuppy.Utils;
12.  
13. using com.mansion.Logic;
14.  
15. namespace com.mansion.Entities.Actors.Mobs
16. {
17.  
18.     public class SenseEntityLogic : SPComponent, ILogic
19.     {
20.  
21.         #region Fields
22.  
23.         [SerializeField]
24.         [EnumFlags]
25.         private IEntity.EntityType _targetEntityType = IEntity.EntityType.Player;
26.  
27.         [SerializeField()]
28.         [DefaultFromSelf()]
29.         private Sensor _eyes;
30.  
31.         [SerializeField]
32.         [AIVariableName]
33.         private string _targetVariable;
34.  
35.         [SerializeField]
36.         [TypeRestriction(typeof(IAIState))]
37.         private Component _onEntityFoundState;
38.  
39.  
40.         //internal stuff
41.         [System.NonSerialized()]
42.         private IEntity _entity;
43.    
44.         #endregion
45.  
46.         #region CONSTRUCTOR
47.  
48.         protected override void Awake()
49.         {
50.             base.Start();
51.  
52.             _entity = SPEntity.Pool.GetFromSource<IEntity>(this);
53.         }
54.  
55.         #endregion
56.    
57.         #region ILogic Interface
58.  
59.         void ILogic.OnEnterState(AILogicController ai, IAIState lastState)
60.         {
61.  
62.         }
63.  
64.         void ILogic.OnExitState(AILogicController ai, IAIState nextState)
65.         {
66.  
67.         }
68.  
69.         ActionResult ILogic.Tick(AILogicController ai)
70.         {
71.             if (_entity.Stalled) return ActionResult.None;
72.  
73.             var aspect = (from a in _eyes.SenseAll()
74.                           let e = SPEntity.Pool.GetFromSource<IEntity>(a)
75.                           where e.Type.HasAnyFlag(_targetEntityType)
76.                           select a).FirstOrDefault();
77.  
78.             IEntity entity;
79.             if (aspect != null && SPEntity.Pool.GetFromSource<IEntity>(aspect, out entity))
80.             {
81.                 ai.Variables[_targetVariable] = entity;
82.                 ai.States.ChangeState(_onEntityFoundState as IAIState);
83.                 return ActionResult.Success;
84.             }
85.  
86.             return ActionResult.None;
87.         }
88.  
89.         #endregion
90.  
91.     }
92.  
93. }
94.  

The code in question is this:

Code (csharp):

1.  
2.             var aspect = (from a in _eyes.SenseAll()
3.                           let e = SPEntity.Pool.GetFromSource<IEntity>(a)
4.                           where e.Type.HasAnyFlag(_targetEntityType)
5.                           select a).FirstOrDefault();
6.  

I'm basically saying give me all entities that the eyes overlap, that have a Entity script, and that Entity type matches the type this sensor targets.

This will grab just anything though... now if we want to do by 'distance' and 'in front of' like you ask in OP... I do this.

Code (csharp):

1.  
2.         private void AttemptActivate()
3.         {
4.             var trans = _entity.transform;
5.             var pos = trans.position.SetY(0f);
6.             var forw = trans.forward.SetY(0f);
7.             var aspect = (from a in _actionSensor.SenseAll()
8.                           where a.gameObject.EntityHasComponent<IEntity>()
9.                           let p = a.transform.position.SetY(0f)
10.                           orderby -a.Precedence, VectorUtil.AngleBetween(p, forw), Vector3.Distance(p, pos) ascending
11.                           select a).FirstOrDefault();
12.             var go = ObjUtil.GetAsFromSource<GameObject>(aspect);
13.  
14.             if (go != null)
15.             {
16.                 IInteractable comp;
17.                 if (go.FindComponent<IInteractable>(out comp))
18.                 {
19.                     switch (comp.InteractWith(_entity))
20.                     {
21.                         case InteractionType.None:
22.                         case InteractionType.Press:
23.                             break;
24.                         case InteractionType.Hold:
25.                             if (_heldInteractable != null) _heldInteractable.Release();
26.                             _heldInteractable = comp;
27.                             break;
28.                     }
29.                 }
30.             }
31.         }
32.  

This is actually on my player motor, and it's how when the player presses 'activate' button I decide which of any nearby objects activate.

Here is the specific linq statement to do it:

Code (csharp):

1.  
2.             var trans = _entity.transform;
3.             var pos = trans.position.SetY(0f);
4.             var forw = trans.forward.SetY(0f);
5.             var aspect = (from a in _actionSensor.SenseAll()
6.                           where a.gameObject.EntityHasComponent<IEntity>()
7.                           let p = a.transform.position.SetY(0f)
8.                           orderby -a.Precedence, VectorUtil.AngleBetween(p, forw), Vector3.Distance(p, pos) ascending
9.                           select a).FirstOrDefault();
10.  

If get all the aspects that are in my sensors view area.
They must have an Entity script (it's just the way I identify things in my game).
I get the position of them, which has the y zero'd out because I don't care about the height of it (my game is flat).
Then I sort them by:
Precedence - so that high priority objects will always be selected first
Angle of forward - so that we get the thing closest to in front of the player
Distance - so it's the closest object to the player

Note the order of these in the 'orderby' is important. It will impact the order of sorting.

In your code you could get a similar result like this:

Code (csharp):

1.  
2. var gos = GameObject.FindGameObjectsWithTag(EnemyFaction);
3. var pos = this.transform.position;
4. pos.y = 0f;
5. var forw = this.transform.forward;
6. forw.y = 0f;
7. var aspect = (from a in gos
8.              let p = a.transform.position.SetY(0f)
9.              orderby Vector.Angle(p, forw), Vector3.Distance(p, pos) ascending
10.              select a).FirstOrDefault();
11.  

 

Thank you for that in depth information! That is a brilliant idea. You deserve some kind of medal for this code and explanation! I'll give this a try!